The present invention relates to a method for secured transmission of visually encoded data, in particular for visual transmission of bar codes, from a mobile end device to a processing unit. The invention further relates to a security element, a mobile end device having such a security element, a processing unit and a system comprising at least one mobile end device and at least one processing unit.
Bar codes, in the form of 1D and 2D bar codes, have been traditionally affixed on printed matter and on physical objects to be read by appropriate bar code scanners. There are many types of bar codes, such as PDF417, microPDF417, MaxiCode, DataMatrix (standard, inverse), QR Code (standard, inverse and micro), Han Xin, Aztec (standard, inverse), etc. and variants. These codes generally work with the same imaging principle.
With increasing availability of mobile devices with auto-focus cameras and bar code scanners, bar codes, in particular 2D bar codes, have started to gain a big role in mobile marketing. The subscribers use their mobile phone to read a bar code that will bring them to a website, display information, and send SMS, etc. The next stage of mobile bar code has started gaining traction, and that is to issue boarding passes, tickets, store cards, coupons, etc. to the mobile phones and to display these bar codes to be read by a cashier, movie counter, shops, etc. Although the same types of bar codes are used, new sets of unanticipated problems have emerged that have never been addressed in prior use cases with printed bar codes.
One of these problems is, for example, that mobile bar codes normally display the underlying data in plain text. In this way, sensitive data, such as for example transaction data, become visible every time a user displays a corresponding bar code. In this way, sensitive data may come into the hands of unauthorized third parties and an undesirable copying of the bar codes coding these data can hardly be prevented.
An encryption of the data, which are displayed through a bar code, by means of a securing key before the generation of the bar code may only partially solve these problems. In case an attacker succeeds in breaking the securing key, all the bar codes encrypted before and in the following by means of the securing key would be compromised.